samsung 55ru7409 no power

[Alschepmist]

Hello to everyone i have a problem with the samsung tv i think the power board are dead but no fuse burnt so the problem was that the tv has no power at all (no red light) then i have opened it i have disconnected the mainboard cable to look if i have backlight on but no backlight .
So the board is a BN4400932Q i have searched for burnt traces but no luck only 3 smd resistor on the backside are yellow like burned but they are not shorted so i searched for 7.5v stb or any other current but nothingfound.
Can anyone help?

[Alschepmist]

Re: samsung 55ru7409 no power

There are som picture

[budm]

Re: samsung 55ru7409 no power

Please upload good clear pictures so we can see what are dealing with. Also provide pictures of the whole backside of the TV showing all the boards.
Did the TV just went dead by itself? History of the TV?

[Alschepmist]

Re: samsung 55ru7409 no power

So thats the backside sorry for quality i hav only the phone.

[Alschepmist]

Re: samsung 55ru7409 no power

And there are the power board so the tv just went dead by itself the tv was working just fine yesterday

[Alschepmist]

Re: samsung 55ru7409 no power

No one?

[budm]

Re: samsung 55ru7409 no power

What DC V do you have on the main filter cap (120uf 450vdc) when measured between the two legs of that cap?

[budm]

Re: samsung 55ru7409 no power

What resistance reading do you get between the two legs of the NT801S?

[Alschepmist]

Re: samsung 55ru7409 no power

315 volt Dc and resistance 0

[budm]

Re: samsung 55ru7409 no power

So ALL 12 pins of the CNM801 show ZERO Volt? How did you probe the EVEN column pins of the CNM801?
I also need the straight shot pictures of the whole top and bottom side of this power supply board.
If you look at your board: https://www.badcaps.net/forum/attach...5&d=1567364621
The center pin of the diode DM856C should have about 7.5VDC with ref to the circuit ground (chassis) when TV is plugged in but not turned on.

[Alschepmist]

Re: samsung 55ru7409 no power

Yes all pin are 0 and at capacitor see picture red pin are 0 volt and blue 316 volt

[budm]

Re: samsung 55ru7409 no power

What did you use for Ground for your meter?
and my post #10:"The center pin of the diode DM856C should have about 7.5VDC with ref to the circuit ground (chassis) when TV is plugged in but not turned on." what do you get on that?

[Alschepmist]

Re: samsung 55ru7409 no power

For cnm801 chasiss for transistor on hot side the 450 v capacitor

[Alschepmist]

Re: samsung 55ru7409 no power

I get 0 the problem is on the hot side

[budm]

Re: samsung 55ru7409 no power

1) and my post #10:"The center pin of the diode DM856C should have about 7.5VDC with ref to the circuit ground (chassis) when TV is plugged in but not turned on." what do you get on that?
2) "for transistor on hot side the 450 v capacitor." Negative leg of the main filter cap for GND for the hot side?

[Alschepmist]

Re: samsung 55ru7409 no power

1) i het 0 volt
2) i use negative leg of main filter

[budm]

Re: samsung 55ru7409 no power

Try re-soldering the transformer pins.

[Alschepmist]

Re: samsung 55ru7409 no power

They are all 0 volt

[budm]

Re: samsung 55ru7409 no power

Did you re-solder those pins as shown in post 17?

[Alschepmist]

Re: samsung 55ru7409 no power

Yes